JP2010211105A - Image forming apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that applies a constant load during image formation even when a transfer roller with a recessed portion formed therein is used. <P>SOLUTION: The image forming apparatus includes: a transfer belt 40 to which an image is transferred; a belt drive roller 41 extending the transfer belt 40; a secondary transfer roller 61 which is disposed opposite to the belt drive roller 41 via the transfer belt and has a recessed portion in the axial direction; a contact member 650 which is disposed on the shaft of the secondary transfer roller 61 and varies in distance from the rotation center of the secondary transfer roller 61 to the periphery thereof; and a contacted member 690 disposed on the shaft of the belt drive roller 41. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention develops a latent image formed on a photosensitive member by developing with a liquid developer composed of toner and carrier, further transfers the developer thereby to a medium such as recording paper, and further on the transferred medium. The present invention relates to an image forming apparatus and an image forming method for forming an image by fusing and fixing a toner image.

Various wet image forming apparatuses that develop a latent image using a high-viscosity liquid developer in which a toner composed of a solid component is dispersed in a liquid solvent and visualize the electrostatic latent image have been proposed. The developer used in this wet image forming apparatus suspends solids (toner particles) in a highly viscous organic solvent (carrier liquid) having electrical insulation properties such as silicon oil, mineral oil, and edible oil. The toner particles are extremely fine with a particle diameter of around 1 μm. By using such fine toner particles, the wet image forming apparatus can achieve higher image quality than a dry image forming apparatus using powder toner particles having a particle diameter of about 7 μm. As an image forming apparatus using such a liquid developer, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2002-156839) discloses an image forming unit that forms an electrostatic latent image on an image carrier, and the image. The electrostatic latent image on the carrier is developed with a developer obtained by dispersing developer particles in a solvent to form a visible image; It has an intermediate transfer medium to which a visual image is transferred and a backup member that comes into contact with the intermediate transfer medium. By pressing the transfer medium against the intermediate transfer medium with the backup member, Transfer means for transferring a visual image to the transfer object, determination means for determining the type of the transfer object to which a visible image is transferred by the transfer means, and the type of transfer object determined by the determination means According to the backup part The image forming apparatus characterized by comprising a control means for variably controlling the pressing force of the transfer member is disclosed by.
JP 2002-156839 A JP 2000-33686 A

  In the image forming apparatus described in Patent Document 1, a backup member that is brought into contact with the intermediate transfer medium is provided, and an urging unit that presses the transfer medium against the intermediate transfer medium is provided by the backup member. ing. By the way, the applicants proposed a structure in which a recess is provided in a member corresponding to the backup member of the image forming apparatus described in Patent Document 1, and a transfer material gripping mechanism for gripping the transfer material is arranged in the recess. However, when such a structure is employed, there is a problem that simply providing a biasing means for the backup member does not allow smooth operation when the concave portion and the intermediate transfer medium face each other.

  In the printing industry, a concentric contact member called a bearer is used to control the contact position between the rollers (Japanese Laid-Open Patent Publication No. 2000-33686 discloses a known example of a bearer of a printing technique). Have been). When transfer is performed in this way, the distance between the rollers is controlled by the mutual bearer, so the transfer pressure differs when the thickness of the transfer material (such as paper) is different. There was a problem that the transfer became unstable.

In order to solve the above problems, an image forming apparatus according to the present invention includes an image carrier on which an image is carried, a transfer roller that is in contact with the image carrier and has a recess in the axial direction. A first peripheral end disposed on the shaft end side of the transfer roller and having a first distance from the rotation center of the transfer roller; and a second from the rotation center of the transfer roller shorter than the first distance. And a support member that contacts the contact member.

In the image forming apparatus according to the present invention, the transfer roller includes an elastic member that urges the image carrier, and the first member of the contact member is positioned at an axial position of the concave portion of the transfer roller. A peripheral end is disposed.

  In the image forming apparatus according to the present invention, the image carrier is an image carrier belt, the belt which stretches the image carrier belt and contacts the transfer roller via the image carrier belt. A tension roller is provided, and the support member is disposed on the axial end portion side of the belt tension roller.

  In the image forming apparatus according to the present invention, the support member has a uniform distance from the rotation center of the belt stretching roller to the peripheral end.

  Further, in the image forming apparatus according to the present invention, the contact member is disposed on the other side of the transfer roller on the axial end side, and the support member is the shaft of the belt stretching roller. It arrange | positions at the other side of a direction edge part side.

  In the image forming apparatus according to the present invention, the image carrier is an image carrier drum, and the support member is disposed on an axial end side of the image carrier drum.

The image forming apparatus according to the present invention includes an image carrier that moves in a first direction and carries an image, a transfer roller that is in contact with the image carrier and has a recess in the axial direction, and the image carrier. A third peripheral end disposed on a second direction orthogonal to the first direction of the body and disposed at a third distance from a rotation center of the transfer roller when facing the transfer roller; And a contact member having a second peripheral end portion arranged at a fourth distance from the rotation center of the transfer roller different from the first distance, and a support member that contacts the contact member. Features.

  Further, the image forming method according to the present invention, the image is carried on the image carrier, a transfer roller having a recess in the axial direction, the transfer material is passed through a transfer nip formed in contact with the image carrier, After the image is transferred to the transfer material and the transfer material passes through the transfer nip, the concave portion of the transfer roller is disposed on the shaft end side of the transfer roller when passing through the transfer nip. A position of the image carrier and the transfer roller by contacting a first peripheral end portion having a first distance from the rotation center of the transfer roller of the contact member and a support member that contacts the contact member It is characterized by regulation.

  As described above, according to the image forming apparatus and the image forming method of the present invention, the transfer roller is urged toward the belt stretching roller, but the shaft portion of the transfer roller has the contact member, and the belt stretching roller Since the shaft has a contact member, when the recess is not in contact with the transfer belt, the transfer roller can apply a predetermined pressure to the transfer nip and the recess faces the transfer belt. In this case, the positional relationship between the transfer roller and the belt stretching roller can be maintained.

  Further, according to the image forming apparatus and the image forming method of the present invention, even when a transfer roller having a recess is used, a constant load state in which a certain pressure is applied to the transfer nip, and between the transfer roller and the belt stretching roller Therefore, the image forming process can be prevented from being adversely affected and the image quality can be prevented from being deteriorated.

  In the printing industry, concentric contact members called bearers are used to control the contact position between rollers. When transfer is performed in this way, the distance between the rollers is controlled by the mutual bearer, so the transfer pressure differs when the thickness of the transfer material (such as paper) is different. The transfer sometimes became unstable. According to the present embodiment as described above, even when the secondary transfer roller 61 having the recess 605 is used, it is possible to ensure a constant transfer pressure even when the thickness of the transfer material such as paper is different. It has become.

1 is a diagram illustrating main components constituting an image forming apparatus according to an embodiment of the present invention. It is a perspective view of a secondary transfer roller used in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram illustrating the operation of a secondary transfer unit 60 in an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a diagram illustrating the operation of a secondary transfer unit 60 in an image forming apparatus according to an embodiment of the present invention. FIG. 10 is a diagram illustrating the operation of a secondary transfer unit 60 in an image forming apparatus according to another embodiment of the present invention. FIG. 10 is a diagram illustrating the operation of a secondary transfer unit 60 in an image forming apparatus according to another embodiment of the present invention. FIG. 10 is a diagram illustrating the operation of a secondary transfer unit 60 in an image forming apparatus according to another embodiment of the present invention. FIG. 10 is a diagram illustrating the operation of a secondary transfer unit 60 in an image forming apparatus according to another embodiment of the present invention. It is a figure explaining the relationship between the contact member 650 and the to-be-contacted part 690. FIG. It is the schematic diagram which expressed the secondary transfer roller, the belt drive roller, and the transfer belt exaggeratedly. FIG. 10 is a diagram illustrating a contact member 650 and a contacted portion 690 in an image forming apparatus according to another embodiment of the present invention. FIG. 10 is a diagram illustrating a contact member 650 and a contacted portion 690 in an image forming apparatus according to another embodiment of the present invention. FIG. 10 is a diagram illustrating a contact member 650 and a contacted portion 690 in an image forming apparatus according to another embodiment of the present invention. FIG. 10 is a diagram illustrating a contact member 650 and a contacted portion 690 in an image forming apparatus according to another embodiment of the present invention. FIG. 5 is a diagram illustrating main components constituting an image forming apparatus according to another embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing main components constituting the image forming apparatus according to the embodiment of the present invention. The developing devices 30Y, 30M, 30C, and 30K are arranged in the lower portion of the image forming apparatus with respect to the image forming units of the respective colors arranged in the central portion of the image forming apparatus, and are transferred to the transfer belt 40, the secondary transfer unit (secondary transfer unit). The configuration of the transfer unit 60, the fixing unit 90, and the like is disposed in the upper part of the image forming apparatus. In particular, since the fixing unit 90 is laid out above the transfer belt 40, the installation area of the entire image forming apparatus can be suppressed. In the present embodiment, a transfer material such as paper that has undergone secondary transfer in the secondary transfer unit 60 is transported to the fixing unit 90 while being sucked by the transfer material transport device 230, the suction devices 210 and 270, and the like. Therefore, such a layout can be realized.

  The developing devices 30Y, 30M, 30C, and 30K are photoconductors 10Y, 10M, 10C, and 10K, corona chargers 11Y, 11M, 11C, and 11K, and exposure units 12Y, 12M, such as an LED array, for forming an image using toner. , 12C, 12K, etc. The photoconductors 10Y, 10M, 10C, and 10K are uniformly charged by the corona chargers 11Y, 11M, 11C, and 11K, and the exposure units 12Y, 12M, 12C, and 12K perform exposure based on the input image signal. Then, electrostatic latent images are formed on the charged photoreceptors 10Y, 10M, 10C, and 10K.

  The developing devices 30Y, 30M, 30C, and 30K generally include liquid developers of respective colors including the developing rollers 20Y, 20M, 20C, and 20K, yellow (Y), magenta (M), cyan (C), and black (K). Developer containers (reservoirs) 31Y, 31M, 31C, 31K to be stored, and application rollers for applying liquid developers of these colors from the developer containers 31Y, 31M, 31C, 31K to the developing rollers 20Y, 20M, 20C, 20K. The anilox rollers 32Y, 32M, 32C, 32K and the like are provided, and the electrostatic latent images formed on the photoreceptors 10Y, 10M, 10C, 10K are developed with the liquid developers of the respective colors.

  The transfer belt 40 is an endless belt, and is stretched around a driving roller 41 and tension rollers 42, 52, and 53. It is rotationally driven by the drive roller 41 while in contact. In the primary transfer portions 50Y, 50M, 50C, and 50K, the primary transfer rollers 51Y, 51M, 51C, and 51K are arranged to face each other with the transfer belt 40 sandwiched between the photoreceptors 10Y, 10M, 10C, and 10K. The developed toner image of each color on the photoreceptors 10Y, 10M, 10C, and 10K is sequentially transferred and transferred onto the transfer belt 40 by using the contact position with 10C and 10K as the transfer position to form a full-color toner image. To do.

  In the secondary transfer unit 60, a secondary transfer roller 61 is disposed opposite to the belt driving roller 41 with the transfer belt 40 interposed therebetween, and a cleaning device including a secondary transfer roller cleaning blade 62 is disposed. Then, at a transfer position where the secondary transfer roller 61 is disposed, transfer of a single-color toner image or a full-color toner image formed on the transfer belt 40 through a transfer material transport path L is performed. Transfer to material.

  Further, on the downstream side of the transfer material conveyance path L, a blower 400 for discharging air to the space between the transfer belt 40 and the secondary transfer roller 61, a first suction device 210, a transfer material conveyance device 230, a first one. The two suction devices 270 are sequentially arranged to convey the transfer material to the fixing unit 90. In the fixing unit 90, a single-color toner image or a full-color toner image transferred onto a transfer material such as paper. Is fused and fixed to a transfer material such as paper.

  The tension roller 42 stretches the transfer belt 40 together with the belt driving roller 41 and the like, and the cleaning device including the transfer belt cleaning blade 49 is brought into contact with the tension roller 42 at a position where the tension roller 42 is stretched. The remaining toner on the transfer belt 40 and the carrier are cleaned. The driving force for driving the transfer belt 40 can be given to the tension roller 42 and the belt driving roller 41 can be used as a simple belt stretching roller.

The transfer material is supplied to the image forming apparatus by a paper feeding device (not shown). The transfer material set in such a sheet feeding device is sent to the transfer material conveyance path L one by one at a predetermined timing. In the transfer material conveyance path L, the transfer material is conveyed to the secondary transfer position by the gate rollers 101, 101 ′ and the transfer material guide 102, and a single color toner development image or a full color toner development image formed on the transfer belt 40 is obtained. Transfer to transfer material. 2
As described above, the next transferred transfer material is further transported to the fixing unit 90 by the transfer material transport means centering on the transfer material transport device 230. The fixing unit 90 includes a heating roller 91 and a pressure roller 92 urged to the heating roller 91 side with a predetermined pressure. A transfer material is inserted between the nips, and the transfer material is placed on the transfer material. The transferred single-color toner image or full-color toner image is fused and fixed on a transfer material such as paper.

  Here, the developing device will be described. Since the configurations of the image forming unit and the developing device for each color are the same, the description will be made based on the yellow (Y) image forming unit and the developing device.

  The image forming unit includes a photoconductor cleaning roller 16Y, a photoconductor cleaning blade 18Y, a corona charger 11Y, an exposure unit 12Y, a developing roller 20Y of the developing device 30Y, a first photoconductor along the rotation direction of the outer periphery of the photoconductor 10Y. A squeeze roller 13Y and a second photoconductor squeeze roller 13Y ′ are arranged.

  The photoconductor cleaning roller 16Y rotates counterclockwise while contacting the photoconductor 10Y, thereby cleaning the untransferred liquid developer and the untransferred liquid developer on the photoconductor 10Y. A bias voltage that attracts toner particles in the liquid developer is applied to the photoconductor cleaning roller 16Y, and the recovered material of the photoconductor cleaning roller 16Y includes a liquid developer rich in solid content that contains a large amount of toner particles. Become.

  On the downstream side of the photoconductor cleaning roller 16Y, the photoconductor cleaning blade 18Y that is in contact with the photoconductor 10Y cleans the liquid developer rich in carrier components on the photoconductor 10Y.

  A cleaning blade 21Y, an anilox roller 32Y, and a compaction corona generator 22Y are arranged on the outer periphery of the developing roller 20Y in the developing device 30Y. A regulating blade 33Y that adjusts the amount of liquid developer supplied to the developing roller 20Y is in contact with the anilox roller 32Y. An auger 34Y is accommodated in the liquid developer container 31Y. Further, a primary transfer roller 51Y of the primary transfer portion is disposed at a position facing the photoconductor 10Y so as to sandwich the transfer belt 40.

  The photoconductor 10Y is a photoconductor drum made of a cylindrical member having a photosensitive layer such as an amorphous silicon photoconductor formed on the outer peripheral surface, and rotates in the clockwise direction.

  The corona charger 11Y is disposed upstream of the nip portion between the photoconductor 10Y and the developing roller 20Y in the rotation direction of the photoconductor 10Y, and a voltage is applied from a power supply device (not shown) to corona-charge the photoconductor 10Y. The exposure unit 12Y irradiates light onto the photoconductor 10Y charged by the corona charger 11Y downstream of the corona charger 11Y in the rotation direction of the photoconductor 10Y, thereby forming a latent image on the photoconductor 10Y. Note that, from the beginning to the end of the image forming process, the configuration of the rollers and the like arranged in the preceding stage is defined to be upstream from the configuration of the rollers and the like arranged in the subsequent stage.

  The developing device 30Y includes a compaction corona generator 22Y that performs a compaction action, and a developer container 31Y that stores a liquid developer in a state where toner is dispersed in a carrier at a weight ratio of approximately 20%.

Further, the developing device 30Y includes a developing roller 20Y that carries the liquid developer, an anilox roller 32Y that is a coating roller for applying the liquid developer to the developing roller 20Y, and a liquid developer amount that is applied to the developing roller 20Y. A regulating blade 33Y for regulating, an auger 34Y supplying the anilox roller 32Y while stirring and conveying the liquid developer, a compaction corona generator 22Y for bringing the liquid developer carried on the developing roller 20Y into a compacted state, and a developing roller 20Y A developing roller cleaning blade 21Y that performs the above cleaning.

  The liquid developer contained in the developer container 31Y is a low-concentration (about 1 to 3 wt%) and low-viscosity volatile at room temperature using a conventionally used Isopar (trademark: exon) as a carrier. Is a non-volatile liquid developer having a high concentration and high viscosity and having non-volatility at room temperature. That is, in the liquid developer in the present invention, a solid having an average particle diameter of 1 μm in which a colorant such as a pigment is dispersed in a thermoplastic resin is introduced into a liquid solvent such as an organic solvent, silicon oil, mineral oil, or edible oil. High viscosity (HAAKE RheoStress RS600, which is added together with a dispersant and has a toner solid content concentration of about 15 to 25%, and has a viscoelasticity of 30 to 30 at a shear rate of 1000 (1 / s) at 25 ° C. (About 300 mPa · s).

  The anilox roller 32Y functions as an application roller that supplies and applies a liquid developer to the developing roller 20Y. The anilox roller 32Y is a cylindrical member, and is a roller having a concave and convex surface formed by grooves engraved in a fine and uniform spiral shape on the surface so as to easily carry a developer on the surface. The anilox roller 32Y supplies the liquid developer from the developer container 31Y to the developing roller 20Y. During operation of the apparatus, as shown in FIG. 1, the auger 34Y rotates counterclockwise to supply the liquid developer to the aniloc roller 32Y, and the aniloc roller 32Y rotates counterclockwise to develop the developing roller 20Y. A liquid developer is applied to the substrate.

  The regulating blade 33Y is an elastic blade having a surface covered with an elastic body, and includes a rubber portion made of urethane rubber or the like that comes into contact with the surface of the anilox roller 32Y. Then, the film thickness and amount of the liquid developer carried and conveyed by the anilox roller 32Y are regulated and adjusted, and the amount of the liquid developer supplied to the developing roller 20Y is adjusted.

  The developing roller cleaning blade 21Y is made of rubber or the like that contacts the surface of the developing roller 20Y. The developing roller 20Y is disposed downstream of the developing nip portion where the developing roller 20Y contacts the photoreceptor 10Y in the rotation direction of the developing roller 20Y. The liquid developer remaining on the roller 20Y is scraped off and removed.

  The compaction corona generator 22Y is an electric field applying means for increasing the charging bias on the surface of the developing roller 20Y. An electric field is applied from the compaction corona generator 22Y to the developing roller 20Y at the compaction site by the compaction corona generator 22Y. The The electric field applying means for compaction may use a compaction roller or the like instead of the corona discharge of the corona discharger shown in FIG.

  The developer carried on the developing roller 20Y and compacted is developed corresponding to the latent image on the photoconductor 10Y by applying a predetermined electric field at the developing nip portion where the developing roller 20Y contacts the photoconductor 10Y.

  The developer remaining after development is scraped off and removed by the developing roller cleaning blade 21Y and dropped into the collecting section in the developer container 31Y to be reused. The carrier and toner that are reused in this way are not in a mixed color state.

The photoreceptor squeeze device disposed upstream of the primary transfer is disposed downstream of the developing roller 20Y so as to face the photoreceptor 10Y and collects excess carrier of the toner image developed on the photoreceptor 10Y. is there. This photoconductor squeeze device is composed of a first photoconductor squeeze roller 13Y and a second photoconductor squeeze roller 13Y ′ made of an elastic roller member that slides in contact with the photoconductor 10Y and is developed on the photoconductor 10Y. It has a function of collecting excess carrier and originally unnecessary fog toner from the toner image and increasing the toner particle ratio in the visible image (toner image). A predetermined bias voltage is applied to the photoconductor squeeze rollers 13Y and 13Y ′.

  The surface of the photoreceptor 10Y that has passed through the squeeze device including the first photoreceptor squeeze roller 13Y and the second photoreceptor squeeze roller 13Y 'enters the primary transfer unit 50Y.

  In the primary transfer portion 50Y, the developer image developed on the photoreceptor 10Y is transferred to the transfer belt 40 by the primary transfer roller 51Y. In the primary transfer portion, the toner image on the photoconductor 10 is transferred to the transfer belt 40 side by the action of the transfer bias applied to the primary transfer backup roller 51. Here, the photoconductor 10Y and the transfer belt 40 are configured to move at a constant speed, and the driving load of rotation and movement is reduced, and the disturbance effect on the visible toner image of the photoconductor 10Y is suppressed.

  In the developing devices 30M, 30C, and 30K, magenta (M), cyan (C), and black (K) toners are respectively formed on the photoreceptors 10M, 10C, and 10K by a process similar to the developing process of the developing device 30Y. Each image is formed. The transfer belt 40 passes through the nip of the primary transfer portion 50 for each color of yellow (Y), magenta (M), cyan (C), and black (K), and a developer (development image) on the photoreceptor of each color. Are transferred, color-superposed, and enter the nip portion of the secondary transfer unit 60.

  The transfer belt 40 that has passed through the secondary transfer unit 60 circulates again to receive the transfer image at the primary transfer unit 50, but on the upstream side where the primary transfer unit 50 is executed, the transfer belt 40 is a transfer belt cleaning blade. 49 or the like is performed for cleaning.

  The transfer belt 40 has a three-layer structure in which an elastic intermediate layer of polyurethane is provided on a polyimide base layer, and a PFA surface layer is provided thereon. Such a transfer belt 40 is used by being stretched by a belt driving roller 41 and tension rollers 42, 52, and 53 on the polyimide base layer side and transferring a toner image on the PFA surface layer side. Since the transfer belt 40 having elasticity formed in this way has good followability and responsiveness to the surface of the transfer material, toner particles having a particularly small particle diameter are transferred to the recesses of the transfer material during the secondary transfer. It is effective for sending and transferring.

  Next, the secondary transfer roller 61 used in the image forming apparatus according to the present embodiment will be described in more detail. FIG. 2 is a perspective view of a secondary transfer roller used in the image forming apparatus according to the embodiment of the present invention. In FIG. 2, 601 is a roller body, 602 is a roller shaft, 605 is a recess, 607 is an elastic member, 610 is a transfer material gripping mechanism, 611 is a transfer material gripping portion, 612 is a transfer material gripping portion receiving portion, and 640 is A transfer material peeling member 650 indicates an abutting member.

Roller shaft portions 602 are provided at both ends of the roller body portion 601 of the secondary transfer roller 61, and are attached to the apparatus main body side so as to be rotatable around the roller shaft portion 602. Further, the roller body 601 is provided with a recess 605 extending in the axial direction, a transfer material gripping mechanism 610 is provided in the recess 605, and an elastic member 607 is provided in the roller body 601 other than the recess 605. Yes. The transfer material gripping mechanism 610 is a mechanism for gripping or releasing the transfer material. The elastic member 607 is composed of a semiconductive elastic rubber layer having an electrical resistance component, and passes through the secondary transfer nip in the secondary transfer unit in a state where a transfer material is wound around the elastic member 607. When the transfer belt 40
The toner image is transferred from the toner to the transfer material.

  In general, the transfer material gripping mechanism 610 is appropriately arranged between a plurality of pairs of transfer material gripping portions 611 and transfer material gripping portion receiving portions 612 provided discretely in the roller axial direction, and between the pairs in the roller axial direction. And a plurality of transfer material peeling members 640 that are formed. All the transfer material gripping portions 611 are configured to be movable, and operate to clamp the transfer material with the transfer material gripping portion receiving portion 612 to grip the transfer material, or to receive the transfer material gripping portion. The transfer material can be released by operating so as to be spaced from the portion 612. All the transfer material peeling members 640 operate so as to push out the transfer material held by the transfer material holding portion 611 and the transfer material holding portion receiving portion 612 in a direction away from the secondary transfer roller 61 side.

  Two contact members 650 are provided at both ends of the roller shaft portion 602 of the secondary transfer roller 61. The contact member 650 has a structure in which a concave portion 605 is provided in the secondary transfer roller 61 when viewed from the roller axial direction and has a contact surface in a region corresponding to the open region. The position between the secondary transfer roller 61 and the belt drive roller 41 is regulated by the contact surface coming into contact with a contacted member to be described later.

  Next, a predetermined pressure is applied at the secondary transfer nip in the secondary transfer portion (secondary transfer unit) 60 composed of the secondary transfer roller 61 provided with the recess 605 for accommodating the transfer material gripping mechanism 610. The structure for regulating the position between the secondary transfer roller 61 and the belt drive roller 41 will be described in detail. 3 and 4 are diagrams for explaining the operation of the secondary transfer unit 60 in the image forming apparatus according to the embodiment of the present invention. In any of the drawings, (A) is a view of the secondary transfer unit 60 as viewed from the side of the apparatus, and (B) is a schematic cross-sectional view of the secondary transfer unit 60. 3 and 4, 650 is a contact member, 670 is a rotation support shaft portion, 671 is a frame member, 672 is an urging member, 689 is a roller shaft portion of the belt driving roller 41, and 690 is a contact member. Each is shown.

  In the secondary transfer unit 60, the roller shaft portion 602 of the secondary transfer roller 61 is rotatably attached to the frame member 671 at both ends thereof. Further, the frame member 671 is rotatable about the rotation support shaft portion 670 and is urged by the urging member 672 in the direction of the arrow in the figure. With such a structure, the secondary transfer roller 61 is biased toward the belt driving roller 41 so that a predetermined pressure can be applied to the secondary transfer nip between the belt driving roller 41 and the secondary transfer roller 61. It has become. By such transfer pressure and transfer bias in the secondary transfer nip, the toner particles on the transfer belt 40 are efficiently transferred to the transfer material side in the secondary transfer nip.

  Two contact members 650 are provided at both ends of the roller shaft portion 602 of the secondary transfer roller 61. Two contacted members 690 are provided at both ends of the roller shaft portion 689 of the belt driving roller 41 so as to correspond to the contact member 650. As shown in FIG. 3B and FIG. 4B, the contact member 650 and the contacted member 690 are arranged so that the positions in the axial direction are aligned.

The contact member 650 has a shape as shown in FIG. 2 and has a contact surface 663 whose distance from the roller rotation center O of the secondary transfer roller 61 is R ₃ . The contact surface 663 is provided in a region corresponding to the open region where the concave portion 605 is provided in the secondary transfer roller 61 when viewed from the roller axial direction. When the concave portion 605 is disposed so as to face the belt driving roller 41 (or the transfer belt 40) in accordance with the operation of the apparatus, the contact surface 663 makes contact with the contacted member 690 on the belt driving roller 41 side. The contacted member 690 receives the biasing pressure of the secondary transfer roller 61 so that the distance and positional relationship between the secondary transfer roller 61 and the belt driving roller 41 are maintained.

  As shown in FIG. 2, the contact member 650 is a member provided at the shaft portion of the secondary transfer roller 61 and having a different distance from the rotation center to the outer periphery of the secondary transfer roller 61, and has a role like a kind of cam. Fulfill.

  The contacted member 690 is a member such as a bearing having an outer periphery whose distance from the roller rotation center O ′ of the belt driving roller 41 is r, and the contact surface 663 of the contact member 650 is accompanied with the rotation of each roller. And the distance and positional relationship between the secondary transfer roller 61 and the belt driving roller 41 are maintained by receiving the load of the secondary transfer roller 61 biased by the biasing member 672. Yes.

  The secondary transfer unit 60 operates in the order of the state shown in FIG. 3, the state shown in FIG. 4, the state shown in FIG. 3, the state shown in FIG. FIG. 3 shows a state where the recess 605 does not face the belt driving roller 41 (or the transfer belt 40). At this time, the urging force from the urging member 672 is applied to the secondary transfer nip, a predetermined transfer pressure is ensured, and further between the secondary transfer roller 61 and the belt driving roller 41. An appropriate transfer bias is applied to the toner particles on the transfer belt 40 to the transfer material side at the secondary transfer nip. In the state shown in FIG. 3, the contact member 650 and the contacted member 690 are completely separated from each other. The distance to the outer periphery excluding the region corresponding to the recess 605 in the contact member 650 is a shape that completely separates from the contacted member 690 so that the biasing force from the biasing member 762 can ensure a predetermined transfer pressure in the transfer nip. Is set to

  FIG. 7 shows a state in which the rotation of each roller has further progressed. The concave portion 605 completely faces the belt driving roller 41 (or the transfer belt 40), and the contact surface 663 of the contact member 650 and the contacted member. 690 shows the situation where each roller rotates while abutting 690. At this time, the urging pressure of the secondary transfer roller 61 urged by the urging member 672 is received by the contacted member 690, and the distance and positional relationship between the secondary transfer roller 61 and the belt drive roller 41. Is retained.

  According to the present embodiment described above, the secondary transfer roller 61 is biased toward the belt driving roller 41, but the shaft portion of the secondary transfer roller 61 has the contact member 650, and the belt driving roller 41. Since the shaft has a structure having a contacted member 690, when the recess 605 is not in contact with the transfer belt, the secondary transfer roller 61 can apply a predetermined pressure to the transfer nip, and the recess When the toner is opposed to the transfer belt, the positional relationship between the secondary transfer roller 61 and the belt driving roller 41 can be maintained.

  By the way, in the printing industry, concentric contact members called bearers are used to control the contact position between rollers (see Japanese Patent Application Laid-Open No. 2000-33686 for known examples of bearers in printing technology). I want to be) When transfer is performed in this way, the distance between the rollers is controlled by the mutual bearer, so the transfer pressure differs when the thickness of the transfer material (such as paper) is different. The transfer sometimes became unstable. According to the present embodiment as described above, even when the secondary transfer roller 61 having the recess 605 is used, it is possible to ensure a constant transfer pressure even when the thickness of the transfer material such as paper is different. It has become.

Next, in another embodiment of the present invention, a secondary transfer unit (secondary transfer unit) 60 that includes a secondary transfer roller 61 provided with a recess 605 for accommodating a transfer material gripping mechanism 610 is provided. A structure for regulating the position between the secondary transfer roller 61 and the belt driving roller 41 while applying a predetermined pressure at the transfer nip will be described in detail. 5 to 8 are diagrams for explaining the operation of the secondary transfer unit 60 in an image forming apparatus according to another embodiment of the present invention. In any of the drawings, (A) is a view of the secondary transfer unit 60 as viewed from the side of the apparatus, and (B) is a schematic cross-sectional view of the secondary transfer unit 60. FIG. 5 to 8, 650 is a contact member, 670 is a rotation support shaft portion, 671 is a frame member, 672 is an urging member, 689 is a roller shaft portion of the belt driving roller 41, and 690 is a contact member. Each is shown. FIG. 9 is a diagram showing a configuration relating to the secondary transfer roller 61, the belt driving roller 41, and the like, and is a diagram for explaining a relationship between the contact member 650 and the contacted portion 690. In FIG. 9, reference numeral 661 denotes a first transfer surface of the contact member 650, 663 denotes a contact surface, and 662 denotes a second transfer surface.

  In the secondary transfer unit 60, the roller shaft portion 602 of the secondary transfer roller 61 is rotatably attached to the frame member 671 at both ends thereof. Further, the frame member 671 is rotatable about the rotation support shaft portion 670 and is urged by the urging member 672 in the direction of the arrow in the figure. With such a structure, the secondary transfer roller 61 is biased toward the belt driving roller 41 so that a predetermined pressure can be applied to the secondary transfer nip between the belt driving roller 41 and the secondary transfer roller 61. It has become. By such transfer pressure and transfer bias in the secondary transfer nip, the toner particles on the transfer belt 40 are efficiently transferred to the transfer material side in the secondary transfer nip.

  Two contact members 650 are provided at both ends of the roller shaft portion 602 of the secondary transfer roller 61. Two contacted members 690 are provided at both ends of the roller shaft portion 689 of the belt driving roller 41 so as to correspond to the contact member 650. As shown in FIG. 5B to FIG. 8B, the contact member 650 and the contacted member 690 are arranged so that the positions in the axial direction are aligned.

The contact member 650 has a shape as shown in FIG. 9 and a contact surface 663 whose distance from the roller rotation center O of the secondary transfer roller 61 is R _3, and first delivery surfaces 66 provided on both sides thereof.
1 and a second delivery surface 662. The contact surface 663 is provided with a recess 605 in the secondary transfer roller 61 when viewed from the roller axial direction, and is provided in a region corresponding to the open region (contact region C ₃ ). When the concave portion 605 is disposed so as to face the belt driving roller 41 (or the transfer belt 40) with the operation of the apparatus, the contact surface 663 (contact region C ₃ ).
The contacted member 690 receives the biasing pressure of the secondary transfer roller 61 by contacting the contacted member 690 on the belt driving roller 41 side, and between the secondary transfer roller 61 and the belt driving roller 41. The distance and the positional relationship are maintained.

With the rotation of the secondary transfer roller 61 and the belt driving roller 41, a constant load state in which a constant pressure is applied to the secondary transfer nip and the positional relationship between the secondary transfer roller 61 and the belt driving roller 41 are constant. However, in each state, the first transfer surface 661 (region C ₁ ) and the second transfer surface 662 provided on both sides of the contact surface 663 are respectively repeated.
By (region C ₂ ), the transition can be made seamlessly without generating vibrations, the influence on the image forming process can be suppressed, and the deterioration of the image quality can be prevented. The first delivery surface 661 (region C ₁ ) and the second delivery surface 662 (region C ₂ ) are formed as tapered surfaces in this embodiment, but may be curved surfaces having a predetermined curvature. .

Contact member 650 shown in FIG. 9, provided on the shaft portion of the secondary transfer roller 61, the distance from the rotation center of the secondary transfer roller 61 to the outer periphery are different (contact area C ₃ and region C ₁ and region This is a member having a different distance from the center of rotation to the outer periphery in C ₂ and other regions, and serves as a kind of cam.

  The contacted member 690 is a member such as a bearing having an outer periphery whose distance from the roller rotation center O ′ of the belt driving roller 41 is r, and the contact surface 663 of the contact member 650 is accompanied with the rotation of each roller. And the distance and positional relationship between the secondary transfer roller 61 and the belt driving roller 41 are maintained by receiving the load of the secondary transfer roller 61 biased by the biasing member 672. Yes.

  As the secondary transfer unit 60 rotates, the state shown in FIG. 5 → the state shown in FIG. 6 → the state shown in FIG. 7 → the state shown in FIG. 8 → the state shown in FIG. Operate. FIG. 5 shows a state where the recess 605 does not face the belt driving roller 41 (or the transfer belt 40). At this time, the urging force from the urging member 672 is applied to the secondary transfer nip, a predetermined transfer pressure is ensured, and further between the secondary transfer roller 61 and the belt driving roller 41. An appropriate transfer bias is applied to the toner particles on the transfer belt 40 to the transfer material side at the secondary transfer nip. In the state shown in FIG. 5, the contact member 650 and the contacted member 690 are completely separated from each other.

FIG. 6 shows a state immediately before the rotation of each roller advances and the recess 605 is about to reach the belt driving roller 41 (or the transfer belt 40). At this time, the first delivery surface 661 (region C ₁ ) of the contact member 650 gradually moves along with the rotation of each roller.
The situation is approaching 90. That is, the distance between the first delivery surface 661 (region C ₁ ) and the contacted member 690 gradually decreases. When the rotation further proceeds, the contact member 650 and the contacted member 690 come into contact with each other at the boundary between the first delivery surface 661 (region C ₁ ) and the contact surface 663 (contact region C ₃ ). The load from the secondary transfer roller 61 side is received by the contacted member 690, and the distance and positional relationship between the secondary transfer roller 61 and the belt drive roller 41 are maintained. Further, at the moment when the contact member 650 and the contacted member 690 come into contact with each other, the concave portion 605 is in a state of facing the belt driving roller 41 (or the transfer belt 40).

FIG. 7 shows a state in which the rotation of each roller has further advanced. The concave portion 605 completely faces the belt driving roller 41 (or the transfer belt 40), and the contact surface 663 (contact region C) of the contact member 650 is shown. ₃ ) shows a state in which each roller rotates while the abutted member 690 abuts. At this time, the urging pressure of the secondary transfer roller 61 urged by the urging member 672 is received by the contacted member 690, and the distance and positional relationship between the secondary transfer roller 61 and the belt drive roller 41. Is retained.

The rotation of each roller further advances, and at the boundary between the contact surface 663 (contact region C ₃ ) of the contact member 650 and the second delivery surface 662 (region C ₂ ), the contact member 650 and the contacted member 690 And the second delivery surface 662 (region C ₂ ) of the contact member 650 and the contacted member 690 are gradually separated from each other. FIG. 8 shows this state. At this time, the concave portion 605 is separated from the belt driving roller 41 (or the transfer belt 40), the elastic member 607 of the secondary transfer roller 61 comes into contact with the transfer belt 40, and the urging force from the urging member 672 is applied. The secondary transfer nip starts. Further, the contact member 650 and the contacted member 690 are separated from each other, and the load from the contact member 650 to the contacted member 690 is also eliminated.

  According to the present embodiment described above, the secondary transfer roller 61 is biased toward the belt driving roller 41, but the shaft portion of the secondary transfer roller 61 has the contact member 650, and the belt driving roller 41. Since the shaft has a structure having a contacted member 690, when the recess 605 is not in contact with the transfer belt, the secondary transfer roller 61 can apply a predetermined pressure to the transfer nip, and the recess When the toner is opposed to the transfer belt, the positional relationship between the secondary transfer roller 61 and the belt driving roller 41 can be maintained.

  According to the above embodiment, even when the secondary transfer roller 61 having the recess 605 is used, a constant load state in which a constant pressure is applied to the secondary transfer nip, the secondary transfer roller 61, the belt driving roller 41, and the like. Since it is possible to seamlessly transition between the state in which the positional relationship between the two is controlled to a predetermined position without causing vibrations, the image forming process is not adversely affected and image quality deterioration is prevented. Can do.

Next, a method for determining the distance R ₃ in the contact member 650 will be described. FIG. 10 is a schematic diagram exaggeratingly illustrating the configuration of the secondary transfer roller 61, the belt driving roller 41, the transfer belt 40, and the like. Also, FIG. 10 shows that the set load by the urging member 672 is applied, and the elastic member 607 disposed on the secondary transfer roller 61 and the transfer belt 40 are contracted by the transfer pressure in the secondary transfer nip portion. It shows the state. 2 is a state in which the transfer material is not inserted in the secondary transfer nip portion. In the image forming apparatus according to the present embodiment, the distance between the rotation center O of the secondary transfer roller 61 and the nip contact surface obtained in the situation shown in FIG. The distance R ₃ is determined, and the distance r of the contacted member 690 is determined by the distance between the rotation center O ′ of the belt driving roller 41 and the nip contact surface.

In the method of determining the distance R ₃ of the contact member 650 as described above, the characteristic point is that the distance R ₃ is determined with reference to the time when there is no transfer material. In general, an image forming apparatus that handles color images performs so-called registration adjustment, which is position adjustment when four colors are superimposed. In this adjustment, a toner image formed on the transfer belt 40 is read by a sensor, By grasping the shift between colors, the exposure timing in the exposure units 12Y, 12M, 12C, and 12K is adjusted. When determining the distance R ₃ of the abutting member 650, With reference to the absence of the transfer material it can be expected to improve the accuracy in registration adjustment.

Further, when the distance R ₃ of the contact member 650 is determined as described above, there is an advantage that generation of vibrations when shifting from the state of FIG. 6 to FIG. 7 can be suppressed. This is because the contacted member 690 and the contacted member 650 come into contact with each other in the situation assumed in FIG. 10 during the transition from FIG. 6 to FIG. 7.

Next, another embodiment of the present invention will be described. FIG. 11 is a diagram illustrating a contact member 650 and a contacted portion 690 in an image forming apparatus according to another embodiment of the present invention. FIG. 11 is a diagram showing a configuration relating to the secondary transfer roller 61, the belt driving roller 41, and the like. In the previous embodiment, as shown in FIG. 9, the substantially upper half of the contact member 650 has a fan shape, and the contact surface 663 (contact region C ₃ ) or the first transfer surface 661 ( The region C ₁ ) and the second delivery surface 662 (region C ₂ ) are formed. In this embodiment, as shown in FIG. 11, the substantially upper half of the abutting member 650 forms a rectangular portion. The contact surface 663, the first transfer surface 661, and the second transfer surface 662 (region C ₂ ) are formed at the edge. According to such a contact member 650, it is possible to obtain the same effect as that of the previous embodiment, and the shape of one contact of the contact member 650 is not greatly changed. It becomes possible to suppress the change of the center of gravity.

Next, another embodiment of the present invention will be described. FIG. 12 is a view for explaining a contact member 650 and a contacted portion 690 in an image forming apparatus according to another embodiment of the present invention. FIG. 12 is a diagram showing a configuration relating to the secondary transfer roller 61, the belt driving roller 41, and the like. In the embodiment shown in FIG. 12, the contact member 650 has a contact surface 663, a first transfer surface 661, and a second transfer surface 662 (region C ₂ ) formed at the edge of one side of the rectangular shape. According to such an abutting member 650, it is possible to obtain the same effect as in the previous embodiment, and since the processing of the abutting member 650 is simple, the abutting member 650 is manufactured at low cost. There is an advantage that you can.

Next, another embodiment of the present invention will be described. FIG. 13 is a diagram illustrating a contact member 650 and a contacted portion 690 in an image forming apparatus according to another embodiment of the present invention. FIG. 13 is a diagram showing a configuration relating to the secondary transfer roller 61, the belt driving roller 41, and the like. In the embodiment shown in FIG. 13, the contact surface 663, the first delivery surface 661, and the second delivery surface 662 (region C ₂ ) are formed at the edge of one side of the sector shape of the contact member 650. According to such an abutting member 650, it is possible to obtain the same effect as in the previous embodiment, and it is possible to obtain the following effect. In the secondary transfer roller 61, the portion where the concave portion 605 is provided becomes light and the balance of the weight becomes poor. However, according to the contact member 650 used in this embodiment, the entire secondary transfer roller 61 is The weight balance can be stabilized.

  Next, another embodiment of the present invention will be described. FIG. 14 is a diagram illustrating a contact member 650 and a contacted portion 690 in an image forming apparatus according to another embodiment of the present invention. FIG. 14 is a diagram showing a configuration relating to the secondary transfer roller 61, the belt driving roller 41, and the like. In the embodiment shown in FIG. 14, a member having an outer periphery with a constant distance from the roller rotation center O, such as a bearing, is used as the contact member 650. A member having a contact surface, a first delivery surface, and a second delivery surface is used. By using such a contact member 650 and a contacted portion 690, it is possible to obtain the same effect as in the previous embodiment.

  The embodiment shown in FIG. 14 can be applied when the diameter of the belt drive roller 41 facing the secondary transfer roller 61 is an integral multiple of the diameter of the secondary transfer roller 61.

  Next, another embodiment of the present invention will be described. FIG. 15 is a diagram showing main components constituting an image forming apparatus according to another embodiment of the present invention. The components denoted by the same reference numerals as those in the previous embodiment are the same components and will not be described in detail. The present embodiment is different from the previous embodiment in that a first transfer roller 95, a second transfer roller 96, and a third transfer roller 97 are used instead of the transfer belt 40.

  Yellow (Y) and magenta (M) toner images are formed on the first transfer roller 95 by the developing devices 30Y and 30M, and cyan (C) is formed on the second transfer roller 96 by the developing devices 30C and 30K. A black (K) toner image is formed. The yellow (Y) and magenta (M) toner images on the first transfer roller 95 and the cyan (C) and black (K) toner images on the second transfer roller 96 are subsequently transferred to the third transfer roller 97. Is transcribed. The secondary transfer roller 61 is biased by a third transfer roller 97 by a mechanism (not shown) so that a predetermined pressure can be obtained at each nip portion during transfer.

  The transfer material gripped by the transfer material gripping mechanism 610 passes through the nip between the third transfer roller 97 and the secondary transfer roller 61, whereby a full-color toner image is formed.

  Similarly to the previous embodiment, two contact members 650 are provided on the roller shaft portion of the secondary transfer roller 61, and a contacted member 690 is provided on the roller shaft portion of the third transfer roller 97. Further, the contact member 65 is formed with a contact surface, a first delivery surface, and a second delivery surface, as in the previous embodiment.

The secondary transfer roller 61 is biased toward the third transfer roller 97, but has a contact member 650 at the shaft portion of the secondary transfer roller 61, and the first transfer shaft at the shaft portion of the third transfer roller 97. And the second contacted member 690, the secondary transfer roller 61 can apply a predetermined pressure to the transfer nip when the recess 605 is not in contact with the transfer roller, and the recess 605. When the is facing the transfer roller, the positional relationship between the secondary transfer roller 61 and the transfer roller can be maintained.

  Further, according to the image forming apparatus and the image forming method of the present invention, even when the secondary transfer roller 61 having the recess 605 is used, a constant load state in which a constant pressure is applied to the transfer nip, the secondary transfer roller 61, Since it is possible to seamlessly shift between the third transfer roller 97 and a fixed position in which the positional relationship between the third transfer rollers 97 is constant without causing vibrations, the image forming process is not adversely affected and the image quality is deteriorated. Can be prevented.

  Note that although various embodiments have been described in this specification, embodiments configured by appropriately combining the configurations of the respective embodiments are also included in the scope of the present invention.

10Y, 10M, 10C, 10K ... photoreceptor, 11Y, 11M, 11C, 11K ... corona charger, 12Y, 12M, 12C, 12K ... exposure unit, 13Y, 13M, 13C, 13K ... First photosensitive member squeeze roller, 13Y ′, 13M ′, 13C ′, 13K ′... Second photosensitive member squeeze roller, 14Y, 14Y ′, 14M, 14M ′, 14C, 14C ′, 14K, 14K ′,. Photoconductor squeeze roller cleaning blade, 16Y, 16M, 16C, 16K ... Photoconductor cleaning roller, 18Y, 18M, 18C, 18K ... Photoconductor cleaning blade, 20Y, 20M, 20C, 20K ... Development roller , 21Y, 21M, 21C, 21K... Developing roller cleaning blade, 22Y, 2 M, 22C, 22K ... compaction corona generator, 30Y, 30M, 30C, 30K ... developing device, 31Y, 31M, 31C, 31K ... developer container, 32Y, 32M, 32C, 32K ... Anilox roller, 31Y, 31M, 31C, 31K ... Developer container, 33Y, 33M, 33C, 33K ... Restricting blade, 34Y, 34M, 34C, 34K ... Auger (feed roller), 40 ... Transfer belt 41 ... Belt drive roller 42 ... Tension roller 45 ... Developer recovery part 46 ... Transfer belt cleaning roller 47 ... Transfer belt cleaning roller cleaning blade 49 ... Transfer belt cleaning blade, 50Y, 50M, 50C, 50K ... primary transfer portion, 51 , 51M, 51C, 51K ... primary transfer backup roller, 52, 53 ... tension roller, 60 ... secondary transfer unit, 61 ... secondary transfer roller, 62 ... secondary transfer roller Cleaning blade, 74... (Cleaning) blade holding member, 85... Secondary transfer unit collection and storage section, 90... Fixing unit, 91... Heating roller, 92. ..First transfer roller, 96... Second transfer roller, 97... Third transfer roller, 101, 101 '... Gate roller, 102... Transfer material guide, 140. 141, toner amount calculation unit, 145 ... transfer material type information storage unit, 146 ... temperature sensor, 147 ... humidity sensor, 150 ... main control , 151, 153, 157, 158... Air volume control unit, 160... Transfer material gripping mechanism control unit, 210... First suction device, 211. 215 ... Airflow generation unit, 230 ... Transfer material transfer device, 231 ... Case unit, 232 ... Suction surface, 233 ... Partition member, 235 ... Airflow generation unit, 250. ..Transfer material transport member, 251... Transfer material transport member drive roller, 252, 253... Transfer material transport member stretching roller, 270... Second suction device, 271. ... Suction surface, 275 ... Airflow generator, 400 ... Blower, 401 ... Case, 402 ... Opening, 405 ... Airflow generator, 601 ... Roller cylinder Part, 602 ... roller shaft part, 605 ... concave part, 607 ... bullet 610... Transfer material gripping mechanism, 611... Transfer material gripping portion, 612... Transfer material gripping portion receiving portion, 640... Transfer material peeling member, 650. ..First transfer surface, 663... Contact surface, 662... Second transfer surface, 670... Rotating support shaft, 671... Frame member, 672. ... Roller shaft, 690 ... Contact member

Claims (8)

An image carrier on which an image is carried; and
A transfer roller in contact with the image carrier and having a recess in the axial direction;
A first peripheral end disposed on the shaft end portion side of the transfer roller and having a first distance from the rotation center of the transfer roller, and a second from the rotation center of the transfer roller shorter than the first distance. A contact member having a second peripheral end portion having a distance;
A support member that contacts the contact member;
An image forming apparatus comprising: The transfer roller has an elastic member that urges the image carrier,
The image forming apparatus according to claim 1, wherein the first peripheral end portion of the contact member is disposed at an axial position of the concave portion of the transfer roller. The image carrier is an image carrier belt;
A belt tension roller that stretches the image carrier belt and contacts the transfer roller via the image carrier belt,
The image forming apparatus according to claim 1, wherein the support member is disposed on an end side in an axial direction of the belt stretching roller. The image forming apparatus according to any one of claims 1 to 3, wherein the support member has a uniform distance from a rotation center of the belt stretching roller to a peripheral end portion. The contact member is disposed on the other side of the transfer roller on the axial end portion side, and the support member is disposed on the other side of the belt stretching roller on the axial end portion side. The image forming apparatus according to claim 3. The image carrier is an image carrier drum,
The image forming apparatus according to claim 1, wherein the support member is disposed on an axial end portion side of the image carrier drum. An image carrier that moves in a first direction and carries an image;
A transfer roller in contact with the image carrier and having a recess in the axial direction;
A third circumference disposed on a second direction orthogonal to the first direction of the image carrier and disposed at a third distance from the rotation center of the transfer roller when facing the transfer roller. An abutting member having an end portion and a second peripheral end portion disposed at a fourth distance from the rotation center of the transfer roller different from the first distance;
A support member that contacts the contact member;
An image forming apparatus comprising: An image is carried on an image carrier,
A transfer roller having a recess in the axial direction is passed through a transfer nip formed in contact with the image carrier, and the image is transferred to the transfer material.
After the transfer material has passed through the transfer nip, when the concave portion of the transfer roller passes through the transfer nip, the rotation center of the transfer roller of the contact member disposed on the shaft end side of the transfer roller An image forming comprising: a first circumferential end portion having a first distance from a first contact portion; and a support member that contacts the contact member, and a position restriction between the image carrier and the transfer roller. Method.

Images